From: Sai Praneeth Prakhya <[email protected]> "/sys/kernel/iommu_groups/<grp_id>/type" file could be read to find out the default domain type of an iommu group. The default domain of an iommu group doesn't change after booting and hence could be read directly. But, after addding support to dynamically change iommu group default domain, the above assumption no longer stays valid.
iommu group default domain type could be changed at any time by writing to "/sys/kernel/iommu_groups/<grp_id>/type". So, take group mutex before reading iommu group default domain type so that the user wouldn't see stale values or iommu_group_show_type() doesn't try to derefernce stale pointers. Cc: Christoph Hellwig <[email protected]> Cc: Joerg Roedel <[email protected]> Cc: Ashok Raj <[email protected]> Cc: Will Deacon <[email protected]> Cc: Sohil Mehta <[email protected]> Cc: Robin Murphy <[email protected]> Cc: Jacob Pan <[email protected]> Signed-off-by: Sai Praneeth Prakhya <[email protected]> Signed-off-by: Lu Baolu <[email protected]> --- drivers/iommu/iommu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 716bd602b0ed..aad465c38067 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -501,6 +501,7 @@ static ssize_t iommu_group_show_type(struct iommu_group *group, { char *type = "unknown\n"; + mutex_lock(&group->mutex); if (group->default_domain) { switch (group->default_domain->type) { case IOMMU_DOMAIN_BLOCKED: @@ -517,6 +518,7 @@ static ssize_t iommu_group_show_type(struct iommu_group *group, break; } } + mutex_unlock(&group->mutex); strcpy(buf, type); return strlen(type); -- 2.25.1
